perf stat: Fix zero total printouts

Before:

           0  sched:sched_switch #        nan M/sec

After:

           0  sched:sched_switch #      0.000 M/sec

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

tools/perf/builtin-stat.c

@@ -338,14 +338,24 @@ static void nsec_printout(int counter, double avg)
 
 static void abs_printout(int counter, double avg)
 {
+	double total, ratio = 0.0;
+
 	fprintf(stderr, " %14.0f  %-24s", avg, event_name(counter));
 
 	if (MATCH_EVENT(HARDWARE, HW_INSTRUCTIONS, counter)) {
-		fprintf(stderr, " # %10.3f IPC  ",
-				avg / avg_stats(&runtime_cycles_stats));
+		total = avg_stats(&runtime_cycles_stats);
+
+		if (total)
+			ratio = avg / total;
+
+		fprintf(stderr, " # %10.3f IPC  ", ratio);
 	} else {
-		fprintf(stderr, " # %10.3f M/sec",
-				1000.0 * avg / avg_stats(&runtime_nsecs_stats));
+		total = avg_stats(&runtime_nsecs_stats);
+
+		if (total)
+			ratio = 1000.0 * avg / total;
+
+		fprintf(stderr, " # %10.3f M/sec", ratio);
 	}
 }